JPH08325542A - adhesive - Google Patents

Abstract

(57) [Summary] [Purpose] To provide an adhesive having excellent leaving stability. An acetoacetic acid ester group-containing polyvinyl alcohol system containing 2% by weight or less of an alkali metal acetate and 5% by weight or less of acetic acid, and having an alkali metal acetate / acetic acid weight ratio of 0.01 to 100. An adhesive containing a resin.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a polyvinyl alcohol resin containing an acetoacetic acid ester group (hereinafter referred to as AA-PVA).
Abbreviated), and more specifically, to an adhesive excellent in storage stability.

[0002]

2. Description of the Related Art Conventionally, PVA has been used as an aqueous solution as it is as an adhesive for various packaging such as corrugated cardboard and bags, and as an adhesive for office work. Various labels, stamps, stamps, shoji paper,
For back glue applications such as wallpaper, fusuma paper, and posters, as hot melt adhesives, for bookbinding, bag making, box making, packaging, woodworking, shoes, textiles, etc. As pressure sensitive adhesives, various labels, tapes, etc. Fast curing adhesives (honeymoon adhesives)
It is used as various adhesives for bonding wood, paper, inorganic materials and the like.

[0003]

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention
When the adhesive is used for the adhesive application as described above, the rewetting adhesive,
Adhesives used in the form of aqueous solutions such as pressure-sensitive adhesives and quick-setting adhesives (honeymoon adhesives) often have problems in storage stability of the aqueous solution, and also in hot-melt adhesives, Since the storage stability is poor and problems such as blocking may occur, a PVA adhesive having excellent storage stability is desired.

[0004]

As a result of intensive studies to solve the above problems, the present inventor has surprisingly found that the alkali metal acetate is contained in an amount of 2% by weight or less and acetic acid is contained in an amount of 5% by weight or less. An alkali metal acetate / acetic acid weight ratio of 0.
The inventors have found that the storage stability of the adhesive using the AA-modified PVA of 01 to 100 is excellent, and reached the present invention. Hereinafter, the present invention will be described in detail.

The method for producing the AA-PVA in the present invention is not particularly limited and may be produced by any method, but it is preferably obtained by reacting PVA with diketene. For example, PVA is dispersed in an acetic acid solvent and diketene is added thereto, and PVA is dissolved in a solvent such as dimethylformamide or dioxane in advance and diketene is added thereto. Also,
A method of directly contacting diketene gas or liquid diketene with PVA having absorbed acetic acid or the like to obtain AA-PVA can also be adopted.

PVA used to obtain AA-PVA
Is not particularly limited, but the residual acetic acid group is 0.1 to 30 mol%, the average degree of polymerization is 50 to 6000 (more preferably 300
.About.3000) and an average degree of saponification of 70 to 99.9 mol%. The degree of AA conversion (content of acetoacetic acid ester group) of the AA-PVA is 0.1 to 30 mol%, more preferably 0.2 to 20 mol%. AA-modified PVA having a degree of AA of less than 0.1 mol% lowers the water resistance of the adhesive, which is not preferable, and conversely, AA-modified PVA having a degree of AA of more than 30 mol% is aqueous (aqueous solution, emulsion,
Aqueous dispersion, etc.) Adhesive solution stability is reduced and discoloration occurs, which is not preferable.

In the present invention, the conventional AA PV as described above is used.
2% by weight or less (preferably 0.01 to 0.3% by weight) of acetate of an alkali metal (sodium, potassium, etc.) and 5% by weight or less (preferably 0.001 to 3) of acetic acid.
%), And the weight ratio of the alkali metal acetate and acetic acid is 0.01 (alkali metal acetate / acetic acid).
To 100 (preferably 0.01 to 10) controlled AA-PVA is the most characteristic feature. When the alkali metal acetate exceeds 2% by weight, a solution of an aqueous adhesive is obtained. A decrease in stability occurs and acetic acid is 5
If it exceeds 5% by weight, acetic acid odor is generated in the adhesive, which is not preferable. When the weight ratio of the alkali metal acetate / acetic acid is less than 0.01, the water resistance and strength of the adhesive cannot be improved. On the contrary, when the weight ratio exceeds 100, the aqueous adhesive solution is used. Stability is reduced, which is not preferable. In addition,
The determination of the above-mentioned alkali metal acetate is carried out by atomic absorption spectrometry with respect to a solution obtained by ashing AA-PVA and then dissolving the ash in a hydrochloric acid aqueous solution under heating. As a method for quantifying acetic acid, a sample is used as an aqueous solution and determined by gas chromatography / mass spectrometry (GC / MS method).

In the present invention, the amounts of the alkali metal acetate and acetic acid contained in the AA-PVA used may be controlled as described above, and the controlling method is arbitrary. For example, the amount of alkali catalyst at the time of saponification at the time of producing bulk PVA is adjusted,
It is optional to add or remove the alkali metal acetate after the production. Regarding the amount of acetic acid, acetic acid may be added after PVA production, or PVA containing a large amount of acetic acid may be washed and dried.

In addition to the raw powder treatment, control may be performed by adding or removing an alkali metal acetate or removing acetic acid during or after the production of AA-PVA. good. Industrially, after manufacturing AA PVA,
A method of removing the alkali metal acetate and acetic acid is practical, and in order to remove the alkali metal acetate, specifically, alcohol cleaning is adopted, and as the alcohol, methanol, ethanol, n-propanol, Examples include isopropanol and the like, but preferably methanol is used. This alcohol cleaning is usually 1 to 1 of PVA.
Use 5 times the weight of alcohol, 0.5 ~ 5 ~ 60 ℃
It is washed about 1 to 3 times under the condition of 2 hours.

Further, in order to remove acetic acid, a method such as distillation under reduced pressure, washing with methanol, drying treatment, filtration and centrifugation is used.
Examples thereof include a method of treating A-PVA, and these treatments may be performed simultaneously or separately, but a drying treatment is preferably adopted. The conditions of the drying treatment differ depending on the device and cannot be generally stated, but it may be carried out at 30 to 80 ° C. for about 10 hours, preferably at 40 to 70 ° C. for about 6 hours. In the present invention, by adjusting the pH of the 4% by weight aqueous solution of such AA-PVA to 3 to 6.5, preferably 4 to 5, the stability of the aqueous solution is further improved and a good molded product is obtained. It becomes possible. The method of adjusting the pH is not particularly limited, and for example, the amount of the alkali catalyst during saponification during the production of the bulk powder PVA is adjusted, or the PVA is adjusted.
It is optional to add or remove acetic acid after production.

If necessary, mineral acids such as hydrochloric acid, sulfuric acid and phosphoric acid, organic acids such as propionic acid and maleic acid, sodium hydroxide, potassium hydroxide, calcium hydroxide,
The pH may be adjusted by adding a primary amine, a secondary amine, a tertiary amine, a quaternary ammonium salt or the like. In addition to the raw powder treatment, the above-mentioned pH adjustment may be performed during or after the production of AA-modified PVA. Industrially, the method of removing acetic acid after the production of AA-modified PVA is practical. Is. Next, the adhesive using the obtained AA-PVA will be described.

Such AA-PVA includes various kinds of adhesives such as rewetting adhesives, hot-melt adhesives, pressure-sensitive adhesives, quick-curing adhesives (honeymoon adhesives), etc., in addition to general adhesives containing the PVA in an aqueous solution. It can be used as an adhesive. As a general aqueous solution adhesive application, the content of the PVA is 1 to
About 30% by weight, a filler, a defoaming agent (or foaming agent),
Additives such as colorants are blended and used for adhesives.
When used as a rewetting adhesive, the PVA is made into an aqueous solution, and then coated on a base material such as gum tape or stamp and dried. At this time, alcohols such as methanol and ethanol, glycols such as ethylene glycol, propylene glycol, polyethylene glycol, and glycerin may be added if necessary. The coating can be performed by a known method such as a gravure coater, a reverse roll coater, an air knife coater, and a spray.

It is also possible to form a rewetting adhesive layer by hot-melt coating. At this time, the PVA-based resin is melted at about 100 to 250 ° C., and an additive such as a plasticizer (polyhydric alcohol such as ethylene glycol or propylene glycol or higher fatty acid ester thereof) is added thereto. And so on,
Roll coater with viscosity of 500-10,000 cps,
The substrate can be coated by a known method such as a doctor coater or spray. Also for hot melt adhesives, additives such as plasticizers are added to the base material by a known method in the same manner as described above, and bookbinding, packaging, woodworking,
It can be used for bonding fibers and the like.

As the pressure-sensitive adhesive, a plasticizer, a tackifier, or the like as described above may be added and coated on a substrate by a known method to be used for bonding a label, a tape or the like. As a quick-curing adhesive (honeymoon adhesive), the PVA
A liquid consisting of an aqueous liquid containing a and an amine compound (melamine, acetoguanamine, benzoguanamine, urea, alkylated methylol urea, alkylated methylol melamine, condensate of acetoguanamine or benzoguanamine and formaldehyde, diethylenetriamine, triethylenetetramine, Aliphatic amines such as tetraethylenepentamine, trimethylhexamethylenediamine, polyetherdiamine, aromatic amines such as metaphenylenediamine, diaminodiphenylmethane, amine adducts, modified amines such as polyamidoamine, etc., aldehyde compounds (formaldehyde, acetaldehyde, Propionaldehyde, monoaldehyde such as butyraldehyde, glyoxal, glutandialdehyde, malondialdehyde, succinial Inorganic salts such as hydr, maleic dialdehyde, dialdehydes such as phthaldialdehyde, etc., hydrazine compounds (hydrazine, hydrazine hydrado, hydrazine hydrochloric acid, sulfuric acid, nitric acid, nitrous acid, phosphoric acid, thiocyanic acid, carbonic acid, etc. and formic acid, Organic salts such as oxalic acid, hydrazine methyl, ethyl, propyl, butyl,
Monosubstituted compounds such as allyl, asymmetric disubstituted compounds such as 1,1-dimethyl, 1,1-diethyl, 4-n-butyl-metal and 1,2-dimethyl, 1,2-diethyl, 1,2-diisopyr Such as symmetrical disubstitution).

Formamide group-containing compounds (vinyl formamide, N-allylformamide, acrylformamide and other monomer polymers or copolymers of these monomers with vinyl acetate monomer, styrene monomer, methyl (meth) acrylate and the like), isocyanate Compounds (tolylene diisocyanate, hydrogenated tolylene diisocyanate, trimethylolpropane-tolylene diisocyanate adduct, triphenylmethane triisocyanate, methylenebis-4-phenylmethane triisocyanate, methylenebisisophorone diisocyanate, methylenebis-4-phenylmethanetriisocyanate Isocyanates and methylenebisisophorone diisocyanate ketoxime blocks), polyvalent metal ions (aluminum acetate, copper acetate, chloride) Luminium, copper chloride, lead chloride, cobalt chloride, iron (III) chloride, aluminum sulfate, iron (III) sulfate, etc.) and other B-containing solutions containing methylol group or alkoxymethyl group-containing compound The liquid A is an aqueous solution or emulsion of the PVA, and in the case of an aqueous solution, the content of the PVA is 2 to
50% by weight is preferable, and 1 to 10 in the case of emulsion.
Weight percent is preferred.

In preparing the emulsion, although not particularly limited, vinyl monomers (vinyl acetate, (meth) acrylic acid ester, vinyl chloride, etc.) containing the PVA as an emulsifier or protective colloid are used. Emulsion polymerization, a method of post-emulsifying a solution or melt of a synthetic resin (polyvinyl acetate, polyvinyl chloride, etc.) in the presence of the PVA, and a synthetic resin (polyvinyl acetate, polyvinyl chloride) obtained by any method. Vinyl chloride, etc.)
Examples thereof include a method of adding VA to obtain a more stable emulsion.

Furthermore, if necessary, other water-soluble polymers such as PVA and starch, crosslinking agents such as polyvalent metals, isocyanates and amino resins, plasticizers, film-forming aids such as high boiling point solvents, calcium carbonate, etc. An extender pigment such as clay and clay, a colored pigment such as titanium oxide, a preservative, an insect repellent, an antifoaming agent, a thickener, an anticorrosive and the like are added to obtain the above liquid A. In addition to the above compounds, the liquid B may further contain a curing accelerator such as amines, alcohols and acids, an anticorrosive such as lecithin and lanolin, an antiseptic, a thickener and the like. When using a fast-curing adhesive (honeymoon adhesive), it is sufficient to apply the above-mentioned liquids A and B to the adherend, respectively, and then bring the coated surfaces into close contact. In some cases, liquids A and B It is also possible to mix and use.

[0018]

[Operation] Since the adhesive of the present invention uses a specific AA-modified PVA, the adhesive has excellent storage stability.
General aqueous solution adhesive, re-wetting adhesive, hot melt adhesive, pressure sensitive adhesive, fast curing adhesive (honeymoon adhesive)
It is very useful for various adhesive applications such as.

[0019]

EXAMPLES The present invention will be specifically described below with reference to examples. In the examples, "%" and "parts" mean weight basis unless otherwise specified. (Production of AA-PVA) AA-P P is prepared by the following method.
VA (PVA-I-VIII) was produced. [PVA-I] PV containing 0.3% sodium acetate
100 parts of A powder (saponification degree 99.4 mol%, degree of polymerization 1200, average particle size 100 mesh) was charged into a kneader,
60 parts of acetic acid was put into this, swelled, rotation speed 20 rpm
The mixture liquid of 25 parts of diketene and 2 parts of acetic acid was added dropwise to the mixture while stirring at 60 ° C. over 4 hours, and the mixture was further reacted for 30 minutes. After the reaction is completed, the reaction dispersion is added to methanol 500
Part of methanol and then dried at 70 ° C. for 6 hours,
AA-modified PVA containing 0.05% sodium acetate and 0.1% acetic acid (sodium acetate / acetic acid weight ratio = 0.5) and having a degree of AA conversion of 6.0 mol% was obtained. Also, such AA
The pH of the 4% aqueous PVA solution was 4.5.

0.3% of [PVA-II] sodium acetate
PVA powder contained (saponification degree 88 mol%, degree of polymerization 13
00, average particle size 200 mesh) was charged in a kneader in an amount of 100 parts, and 15 parts of liquid diketene was added by spraying at room temperature for 30 minutes while stirring at a rotation speed of 60 rpm.
The temperature was raised to 60 ° C. and the reaction was carried out for 3 hours. After the reaction, the reaction mixture was washed 3 times with 50 parts of methanol, and then sodium acetate was added to 0.
After adding 05 parts, it was dried at 60 ° C. for 8 hours, and contained 0.05% sodium acetate and 0.01% acetic acid (weight ratio of sodium acetate / acetic acid = 5), AA degree of 3.3 mol%.
A PVA composition of AA was obtained. In addition, such AA PV
The pH of the 4% aqueous solution of A was 4.8.

[PVA-III] sodium acetate 0.3%
% PVA powder (saponification degree 88 mol%, degree of polymerization 1
300, average particle size 100 mesh) in a kneader 100
8 parts of diketene gas generated in the evaporator was allowed to flow into the reactor while the temperature was raised to 90 ° C. over 1 hour while stirring the parts and stirring at a rotation speed of 20 rpm. After heating to 90 ° C. and stirring for another 30 minutes, 5 parts of water and 10 parts of acetic acid were sprayed and mixed, and dried under reduced pressure (100 mmHg) at 60 ° C. for 8 hours to obtain 0.1% sodium acetate and 2 parts acetic acid. % (Sodium acetate / acetic acid weight ratio = 0.05) A
AA-PVA having a degree of A conversion of 3.1 mol% was obtained. The pH of a 4% aqueous solution of such AA-PVA was 3.5.

[PVA-IV] In the above-mentioned production of PVA-I, washing with 500 parts of methanol was added once more, and the drying conditions were changed to 70 hours at 70 ° C. under reduced pressure (100 mmHg). Manufacture and add sodium acetate to 0.
AA-modified PVA containing 0075% and acetic acid 0.001% (sodium acetate / acetic acid weight ratio = 7.5) and having a degree of AA conversion of 3.1 mol% was obtained. Also, 4% of such AA-PVA
The pH of the aqueous solution was 5.8.

[PVA-V] In the above production of PVA-I, the amount of methanol was changed to 100 parts and the drying condition was changed to 4
The same procedure was repeated except that the temperature was changed to 0 ° C. for 6 hours, and the mixture contained 0.2% sodium acetate and 5.3% acetic acid (sodium acetate / acetic acid weight ratio = 0.04). AA degree 6.0 mol %, 4% aqueous AA-PVA having a pH of 2.8 was obtained. [PVA-VI] In the production of the above-mentioned PVA-I AA-PVA, the drying conditions are reduced pressure (100 mmHg) 70 ° C.
Was carried out in the same manner as above, except that the content was changed to 6 hours, and sodium acetate 0.2% and acetic acid 0.001% were contained (sodium acetate / acetic acid weight ratio = 200).
AA PVA having a pH of 5.8 in a 4% aqueous solution was obtained.

[PVA-VII] In the production of AA-PVA of PVA-I, 1.7 parts of sodium acetate was added at the end of the (AA-forming) reaction, and the mixture was stirred and dried under reduced pressure (100 mmHg). The same procedure was repeated except that the temperature was changed to 70 ° C. for 4 hours, and sodium acetate was 2.2% and acetic acid was 0.1%.
Contains 25% (weight ratio of sodium acetate / acetic acid =
8.8) AA-PVA having a degree of AA of 6.0 mol% and a pH of a 4% aqueous solution of 5.3 was obtained. [PVA-VIII] P containing 0.1% sodium acetate
100 parts of VA powder (saponification degree 99.5%, degree of polymerization 1200, average particle size 200 mesh) was charged into a kneader, to which 30 parts acetic acid, 30 parts methyl acetoacetate and 2 parts sulfuric acid were added and stirred at 80 ° C. While reacting for 8 hours, after completion of the reaction, washed with 50 parts of methanol, dried at 60 ° C. for 4 hours,
AA-modified PVA containing 0.02% sodium acetate and 4% acetic acid (sodium acetate / acetic acid weight ratio = 0.005) and having a degree of AA conversion of 6.0 mol% and a 4% aqueous solution pH of 2.5 was obtained. .

Example 1 After preparing a 10% aqueous solution of PVA-I as described above, in order to examine the storage stability of the aqueous solution, the viscosity (a) at 25 ° C.
Brookfield viscometer [rotor (No. 1)
Rotation speed of 5 rpm], the aqueous solution was left in a constant temperature bath at 60 ° C. for 1 month, the viscosity (b) of the aqueous solution was measured again, and the viscosity ratio of (b) / (a) was determined. Further, in order to investigate the storage stability of the powder, 6 parts of the above PVA-I powder was used.
After leaving it in a thermostatic chamber at 0 ° C and 65% RH for 3 months,
The viscosity (c) of a 0% aqueous solution was measured in the same manner as above,
The viscosity ratio of (c) / (a) was determined. In addition, the PVA-I before each of the above-mentioned standing treatment and after standing for one month at 60 ° C
10% aqueous solution of A was used as a solution, and a 5% aqueous solution of adipic dihydrazide was used as a solution of B to prepare a quick-curing adhesive (honeymoon adhesive). ² and B solution 50 g / m ² are applied,
After crimping at 3 kgf / cm ² for 10 seconds, JIS K
The adhesive force was measured according to 6849 (Test method for tensile adhesive strength of adhesive).

Examples 2 to 4 and Comparative Examples 1 to 4 Using the AA-modified PVA shown in Table 1, the viscosity ratio and the adhesive force were measured in the same manner as in Example 1. The measurement results of Examples and Comparative Examples are shown in Tables 1 and 2.

[0027]

Table 1 Types of viscosity storage stability of AA-modified PVA (a) (cps) (b) / (a) (c) / (a) viscosity ratio Viscosity ratio Example 1 PVA-I 250 2.0 1.1 〃 2 PVA-II 260 2.1 1.1 〃 3 PVA-III 260 2.5 1.2 〃 4 PVA-IV 260 3.0 1.2 Comparative Example 1 PVA-V 250 ＊＊＊ 〃 2 PVA-VI 250 *** 〃 3 PVA-VII 250 *** 〃 4 PVA-VIII 250 **** 60 ° C, (b) was not measured because the aqueous solution gelled after left for 1 month. ** (c) was not measured because the powder after standing for 3 months at 60 ° C, 65% RH was not completely dissolved in water.

[0028]

[Table 2] Initial adhesive strength (kg / cm ² ) Normal adhesive strength (kg / cm ² ) Before standing treatment After standing treatment Before standing treatment After standing Example 1 2.8 2.9 11.2 11.3 〃 2 3.0 3.1 11.4 11.4 〃 3 3.0 3.1 11.4 11.4 〃 4 3.0 3.1 11.4 11.5 Comparative Example 1 2.8 * 11. 4 * 〃 2 2.8 * 11.4 * 〃 3 2.8 * 11.3 * 〃 4 2.8 * 11.4 * Note) The initial adhesive force and normal adhesive force are the adhesive force immediately after crimping and The adhesive strength after standing for 7 days at room temperature is shown, and the terms "before standing treatment and after standing treatment" mean the adhesive strength using AA-PVA before standing treatment and after standing for 1 month at 60 ° C. * Since the solution A gelated and it was impossible to apply it, measurement was not performed.

[0029]

EFFECT OF THE INVENTION The adhesive of the present invention is a specific AA-modified PVA.
Since the adhesive is excellent in storage stability, general aqueous solution adhesives, rewetting adhesives, hot melt adhesives, pressure-sensitive adhesives, fast-curing adhesives (honeymoon adhesives) It is very useful for various adhesive applications such as.

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Claims (2)

[Claims] 1. An alkali metal acetate of 2% by weight or less,
An adhesive comprising an acetoacetate ester group-containing polyvinyl alcohol resin containing 5% by weight or less of acetic acid and having an alkali metal acetate / acetic acid weight ratio of 0.01 to 100. 2. The alkali metal acetate is added in an amount of 0.01 to 0.
3% by weight, 0.001 to 3% by weight of acetic acid, and an acetoacetic acid ester group-containing polyvinyl alcohol resin having an alkali metal acetate / acetic acid weight ratio of 0.01 to 10 An adhesive characterized by.